AIM-HIGH is a multicenter controlled clinical trial designed to test the hypothesis that the drug combination of extended-release (ER-) niacin plus simvastatin is superior to simvastatin alone, at comparable levels of intreatment LDL-cholesterol, for delaying the time to first occurrence of clinically relevant cardiovascular (CV) disease outcomes over a 4-year median follow-up. Large 5-yr clinical trials have found only 25-35% CV risk reduction using statin monotherapy (i.e., event rate 2/3 to 3/4 of placebo rate). Thus, this study is needed to confirm the more substantial (>50%) treatment benefit predicted for the statin-niacin combination by epidemiology and by preliminary clinical trials. The target population is men and women >45 years old with established CV disease and at higher risk due to the two dyslipidemic elements of metabolic syndrome (MS) -- low HDL-cholesterol (HDL-C) [40 mg/dl or less] and high triglycerides (TG) [150 mg/dl or greater]. The proposed study specifically aims to test this hypothesis for the primary composite clinical endpoint of CV death, nonfatal myocardial infarction (Ml), non-hemorrhagic stroke, or hospitalization for high-risk acute coronary syndrome with objective evidence of ischemia (troponin-positive or ST-segment deviation). A secondary endpoint is the composite of CV death, non-fatal Ml, or non-hemorr-hagic stroke. The above hypotheses will also be tested among the very large subgroup of these patients who meet the current or future evolving criteria for metabolic syndrome. The 3300-patient sample, to be recruited in 54 centers in US and Canada, will have up to 85% power to confirm a 29% risk reduction, relative to statin monotherapy, for the rigorous triple endpoint above, and >90% power for the primary endpoint. This companion grant describes the Clinical Trial Center for AIM-HIGH and methodologies for trial coordination, site identification, initiation, and management, data management and biostatistical support.